The present invention is directed to a gas flow control device and more specifically to a gas flow control device for use in oil wells producing by continuous gas-lift. Such a gas flow control device is sometimes referred to in the industry as a gas-lift valve having a housing and a valve seat. The latter terminology is used throughout the specification.
At wells where production is by continuous gas-lift a valve commonly used in working of the well is referred to as a gate valve. It is the valve which lets in gas from between the annulus and the production pipe, into the latter. At a given stage of well discharge production is carried out by means of this gas.
Gate valves consist mainly of a gate which is preset at a given diameter, which does not change as long as the valve is within the well. Flow of gas past this gate is highly irreversible and therefore much load is lost and also it is difficult to calculate rate of flow of gas past the valve, thereby complicating any design or examination.